Intel Core i7-4770K Review: Haswell Has Landed
Intel’s 4th Generation Core processors featuring the Haswell microarchitecture look similar to the Sandy Bridge and Ivy Bridge processors that came before, but these new chips require a new socket, LGA 1150. Along with the new socket, Haswell-based 4th Generation Core processors require motherboards built around Intel’s 8-Series chipsets as well, but we should note that heatisnks compatible with socket LGA 1155/1156 will also work with LGA 1150 processors -- which is a good thing for the average consumer and OEMs alike.
The processor you see pictured here will be Intel’s flagship 4th Generation Core processor at launch, the Core i7-4770K. We’ll have more details on this particular processor on the pages ahead, but to quickly summarize, the Core i7-4770K is a quad-core part with a base clock of 3.5GHz and maximum Turbo clock of 3.9GHz. It features Intel HD 4600 series on-die graphics (formerly known as GT2), and since it is a K-SKU, it is fully unlocked. Along with the Core i7-4770K, Intel is launching a bevy of other processors for various form factors and price points. We’ll have more information on those other processors a little later on as well.
Underneath their integrated heat-spreader, quad-core 4th Generation Core processors sport a rectangular die of roughly 177mm2. The processors are manufactured using Intel’s advanced 22nm process node with tri-gate transistors and they feature more powerful on-die graphics than before, a new CPU microarchitecture, and number of other tweaks and enhancements as well. Haswell supports new power states and supports connected standby. It also features new AVX 2.0 instructions that can improve floating point performance with some workloads by 2X. Haswell also has a fully integrated voltage regulator as well, which is actually part of the CPU die itself. The fully integrated voltage regulator, or FIVR as it is known, frees up motherboard area and saves OEM some costs too, but FIVR also results in other benefits like more dynamic power arrangements and increased efficiency (FIVR is on all Haswell processors, not just mobile parts).
The Haswell microarchitecture leverages technology from previous generation Intel processors, but much of the CPU (and the platform) has been updated to increase performance and power efficiency, and to ensure good scaling. Intel has stated that Haswell scales so well, it will find its way into a wide range of form factors, ranging from Tablet PCs to big-iron servers. The key pipelines in the processor remain largely unchanged over Ivy Bridge, though Haswell features improved code fetch and better brand prediction and more Out-Of-Order resources. There are two additional dispatch ports in the processors, a larger L2 TLB (translation look-aside buffer), and the bandwidth to the processor’s cache has been doubled.
As we’ve mentioned, Haswell-based 4th Generation Core processors also feature Intel’s Advanced Vector Extensions 2.0, or AVX 2. AVX 2 essentially doubles up on the AVX instructions first introduced with Sandy Bridge. AVX 2.0 supports 256-bit integer vectors and adds hardware FMA units to the core. Haswell can perform double the number of single and double-precision FLOPs as Sandy Bridge and AXV 2 adds new integer and gather instructions as well. That double-bandwidth cache we mentioned earlier was introduced to keep the wider vector units in Haswell fed.
Another major addition coming with some Haswell-based 4th Generation Core processors in an on-package eDRAM cache. This 128MB eDRAM cache is one of the ways Intel was able to improve the performance of its top-end Iris Pro GT3e graphics engine, but it’s actually a fully coherent L4 cache that can be shared between the CPU and GPU. The eDRAM cache is co-located on the CPU package (it’s not part of the die) and offers 50+GB/s of read/write bandwidth. We’re told the eDRAM cache at idle uses only about 1/2w to 1w of power, and up to 3.5w to 4.5w when it’s fully utilized, but it can also be powered down when not in use. As of today though, none of Intel's socketed 4th Gen processors will feature this eDRAM--it's currently reserved for premium mobile parts.